The present invention generally relates to electro-optic devices and apparatus incorporating such devices. In particular, the invention relates to electro-optic devices used in architectural windows or vehicular rearview mirror elements.
Electro-optic rearview mirror elements are becoming more common in vehicular applications with regard to both inside and outside rearview mirrors and mirror assemblies, whether on the driver's or the passenger's side. Such electro-optic rearview mirrors are automatically controlled to vary the reflectivity of the mirror in response to rearward and forward aimed light sensors so as to reduce the glare of headlamps in the image reflected to the driver's eyes. Typical electro-optic elements, when incorporated in vehicular rearview mirror assemblies, will have an effective field of view (as defined by relevant laws, codes and specifications) that is less than the area defined by the perimeter of the element itself. Often, the effective field of view of the element is limited, at least in part, by the construction of the element itself and/or an associated bezel.
Various attempts have been made to provide an electro-optic element having an effective field of view substantially equal to the area defined by its perimeter. Assemblies incorporating these elements have also been proposed. FIG. 1A shows an exploded view of a portion of a rearview mirror subassembly 100 as used in a typical exterior rearview mirror assembly. As shown in FIG. 1B, the subassembly 100 includes an electrochromic mirror element 110, a bezel 115, and a carrier plate 117. The subassembly may further include gaskets 120 and 122 that are placed on either side of electrochromic mirror element 110 to form a secondary seal around the periphery of the mirror element 110. As shown in FIG. 1B, electrochromic element 110 includes a front substantially transparent element 130 typically formed of glass and having a front surface 130a and a rear surface 130b. Electrochromic element 110 further includes a rear element 140, which is spaced slightly apart from the element 130. A seal 146 is formed between elements 130 and 140 about their periphery so as to define a sealed chamber 147 therebetween, in which an electrochromic medium is provided. Elements 130 and 140 preferably have electrically conductive layers (serving as electrodes, not shown) on the surfaces facing the chamber such that an electrical potential may be applied across the electrochromic medium. These electrodes are electrically isolated from one another and separately coupled to a power source by means of first and second bus connectors 148a and 148b. To facilitate connection of bus connectors 148a and 148b, elements 130 and 140 are typically vertically offset so that one bus connector may be secured along a bottom edge of one of the elements and another bus connector may be secured to the top edge of the other element. The bus connectors 148a and 148b are typically spring clips (similar to those disclosed in commonly-assigned U.S. Pat. Nos. 6,064,509 and 6,062,920) and are configured to ensure that they remain physically and electrically coupled to the electrode layers on the inward-facing surfaces of elements 130 and 140. Once the electrochromic element 110 has been manufactured and bus clips 148a and 148b attached, then the mirror subassembly 100 may be formed. As shown in FIGS. 1A and 1B, bezel 115 includes a front lip 151, which extends over a portion of the front surface 130a of the front element 130. Typically, the front lip 151 extends over a sufficient portion of front surface 130a to obscure a person's view of the seal 146 and protect the seal 146 from possible degradation caused by ambient UV light. As apparent from FIG. 1B, the width D1 of the front lip 151 of the bezel 115 depends upon a number of factors including an offset distance D2 between the elements 130 and 140. The width D1 may also depend on the degree to which the bus connector clips 148a and 148b extend beyond the peripheral edges of elements 130 and 140. Typical bezels in the related art have a front lip with a width D1 of 5 mm or more.
Prior to inserting the electrochromic mirror element 110 in the bezel 115, an optional front gasket 120 may be provided behind the front lip 151 so as to be pressed between the front surface 130a of the front element 130 and the inner surface of the front lip 151 of bezel 50. The mirror element 110 is then placed in bezel 115 and an optional rear gasket 122 may be provided along the periphery of the back surface of element 140. In lieu of, or in addition to front and/or rear gaskets 120, 122 the bezel/mirror interface area may be filled or potted with a sealing material such as urethane, silicone, or epoxy. A carrier plate 117, which is typically formed of an engineering grade rigid plastic or a similar material as used for bezel 115, is then pressed against the rear surface of element 140 with the gasket 122 compressed therebetween. A plurality of tabs 152 may be formed inside of the bezel such that carrier plate 70 is snapped in place so as to secure mirror element 110 within the bezel. The carrier plate 117 is typically used to mount the mirror subassembly within an exterior mirror housing. More specifically, a positioner (shown below as element 6540 in FIG. 65) may also be mounted within the mirror housing and mechanically coupled to the carrier plate 117 for enabling remote adjustment of the position of the mirror subassembly within the housing.
While the above-described structure is readily manufacturable, styling concerns have arisen with respect to the width of the front lip of the bezel of an electrochromic mirror subassembly. Specifically, the width of the front lip of the bezel of an EC-mirror has been typically made wider than that of any bezel used on non-dimming (non-electro-optic) mirrors due to the need to obscure and hide from view a mutual positional offset of elements 130 and 140 (introduced to accommodate electrical buss clips) and the seal between the substrates. In fact, in non-dimming mirrors bezels are often not used at all. In some vehicles, only the exterior mirror on the driver's side is electro-optic, while the passenger side mirror is non-dimming. Thus, there exists the need for an improved electro-optic mirror element and an improved electro-optic exterior mirror subassembly that has a reduced bezel front width or that does not include a front bezel at all.